Monoclonal antibodies will be raised to peripheral blood leukemia cells and leukemic cell lines by the mouse hybridoma technique. Out first priority will be to detect AML or T ALL specific or associated antigens. Because of our automated screening facilities we will test the hybridoma supernatants by complement dependent cytotoxicity. We have leukemia cells stored in small aliquots in liquid nitrogen from hundreds of different patients which will enable us to obtain the specificity of the antibodies in a few days. When the hybridoma is cloned, stable and its serological specificity known then the molecular weight of the antigen it detects will be determined by immunoprecipitation followed by SDS polyacrylamide gel electrophoresis. At this stage, we will also test the antibodies against normal bone marrow cells by immunofluorescence and colony forming assays (CFU-C, CFU-E). Monoclonal antibodies which react with leukemia but do not appear to react with normal cells may have clinical use in immunodiagnosis or immunotherapy. Using immunofluorescence will determine if positive leukemia cells can be detected in clinically "remission" marrows with the possibility of the early detection of relapse. These leukemia assocated antibodies also may be useful in reclassifying leukemia according antigenic subtypes. Human monoclonal antibodies will be produced from hybridomas of human myeloma cells and human spleen cells from leukemic cadaver donors.